Honing devices



W. P. KUSHMUK HONING DEVICES Oct. 24, 1961 2 Sheets-Sheet 1 Filed Aug.29, 1958 INVENTOR. ZUalier 1? lus/zmak Oct. 24, 1961 w. P. KUSHMUK3,005,294

HONING DEVICES Filed Aug. 29, 1958 2 Sheets-Sheet 2 AWL-MEL 6 INVENTOR.

BY 1% r- -a 9- W 3,005,204 HONING DEVICES Walter P. Kushmuk, Chicago,Ill., assignor to on Tools, Inc, North Chicago, BL, a corporation of1111- nois Filed Aug. 29, 1958, Ser. No. 758,034 11 Claims. (Ci.51-1842) This invention relates to a honing device for cylinders and itis an object of the invention to provide an improved device of thischaracter.

In apparatus incorporating a cylinder with a piston movable therein, itis occasionally desirable that the walls of the cylinder be polished,all as is well recognized in the ant. Such polishing may or may not bepreceded by reboring of the cylinder. A common example of such apparatusis the brake cylinders of automobiles and trucks. A honing deviceconstructed in accordance with the present invention is well adapted topolishing of brake cylinders, and, in particular, lends itself to use bycommon garage mechanics. Such a honing device is, for example,inexpensive, such that it may readily be the personal tool of any garagemechanic. Also it becomes a complete working tool when employed with asmall, hand type electric drill. Still further, it requires no specialtraining for its proper use.

The device automatically adapts itself to a wide range of cylinderdiameters, and is readily adjustable as to the pressure with which thecylinder wall polishing elements bear against the cylinder walls. Stillfurther, the device is collapsible to the extent that it occupies a verysmall space in a mechanics tool chest when not in use.

Various specific structural details of the preferred embodiment of theinvention, especially the use of only two honing elements, greatlysimplify its manufacture and thereby make it much less expensive tomanufacture than previously known devices of the same category. In thepreferred embodiment of the invention the hone carriers may be replacedafter extended use Without special tools and without danger of improperassembly.

Accordingly, it is another object of the invention to provide a honingdevice which is collapsible to a smaller diameter than previously knowndevices of the same category.

It is still another object of the invention to provide g n improvedhoning device which is extremely simple in its construction and istherefore economical to manufacture.

Another object of the invention is to provide an improved honing devicehaving only two honing elements.

Still another object of the invention is to provide an improved honingdevice having a novel construction for connecting the hone carriers tothe supporting arms which permits ready replacement of worn boneswithout special tools or danger of improper assembly.

it is a further object of the invention to provide an improved honingdevice having various of the characteristics specified above while beingof rugged design and efiicient in use.

This invention, together with further objects and advantages thereof,will best be understood by reference to the following description takenin connection with the accompanying drawings, and its scope will bepointed out in the appended claims.

In the drawings, in which like parts are designated by like referencenumerals:

FIGURE 1 is an elevational view of a honing device illustrating thepreferred embodiment of the invention;

FIG. 2 is an end view of the same device;

FIG. 3 is a view similar to FIG. 1 but partially broken away and showingthe honing device in a different position of adjustment;

3,005,294 Patented Oct. 24, 1961 ice FIG. 4 is a side elevation of anarm member included in the apparatus of FIGS. 1-3;

FIG. 5 is a bottom view of the arm of FIG. 4;

FIG. 6 is a left end view of the arms of FIGS. 4 and 5;

FIG. 7 is a cross-sectional view of a honing unit 1ncluded in theapparatus of FIGS. l3;

FIG. 8 is an enlarged partial view showing cooperation between thehoning unit of FIG. 7 and the arm of FIGS. 4-6.

FIG. 9 is a perspective view showing a second form of honing unit; and

FIG. 10 is a reduced, fragmentary, sectional view showing the unit ofFIG. 9 in place on the end of an aim.

The embodiment of the invention illustrated in the drawings has a shank11 which is adapted to be readily received in the chuck of a drill orother suitable rotating device, and a drive stem 12 which is secured tothe shank through a short section of conventional flexible shafting 13.Use of the latter is conventional in honing devices and accordingly itis not described in detail herein. Arranged on the drive stem 12 are acollar 14 which is freely slidable thereon, a knurled nut 15 engagingthreads 16 on the drive stem, and a spring 17 which is compressiblebetween the collar 14 and the knurled nut 15. Two arms 20 are pivot-allysecured to the drive stem 12 substantially in diametrical alignment by apin 21, one of such arms 20* being shown in greater detail in FIGS. 4-6.

The ends of the arms 20* which are pinned to the drive stem 12 arechannel shaped, each arm including channel legs or flanges 22 and achannel base or web 23. The flanges have aligned openings 24 forreceiving the pin 21. As seen in FIGS. 1-3, these channel shapedportions of the two arms 20 open toward each other and the flangesthereof overlap such that the pin 21 may pass through all four openings24 of the two pairs of flanges 22. This construction permits the arms 20to pivot inwardly to substantially parallel positions as illustrated inFIG. 3.

As best seen in FIG. 4, the flanges 22 have inclined or bevelled innerend edges 25 such that the tips 26 of the flanges 22 extend beyond theweb 23. Still further, the web 23 is cut away such that it terminatesoutwardly of the openings 24, that is, to the right of the openings, asviewed in FIG. 4. This abbreviation of the web 23 permits the arms 20 topivot outwardly to a substantial angle without interference between theweb and either the drive stem 12 or the edges of the flanges of theother arm.

With the arms 20 in the position shown in FIG. 3, it will be seen thatif the spring 17 is under compression the collar 14 is made to bearagainst the tips 26 of the flanges by force of the spring 17. This urgesthe arms 20 to pivot outwardly toward the position of FIG. 1 with aforce depending upon the position of adjustment of the nut 15. It willalso be apparent that when the arms 20 reach the position of FIG. 1, thecollar 14 bears against the bevelled edges 25 of the channel legswhereby further outward pivotal movement of the arms is arrested. In thepreferred embodiment of the invention illustrated in the drawings theangle between the bevelled edges 25 and the general longitudinal axis ofthe corresponding arm is 50, as indicated in FIG. 4. This permits eacharm to have a maximum angle of outward movement of 40". When the arms 20are in their inward or substantially parallel positions, the spring 17is at maximum compression, with a given setting of the knurled nut 15;but the torque arm, measured laterally from either-"of the tips 26 tothe pin 21, is at a minimum. As the arms are permitted to pivotoutwardly the spring 17 expands and thus exerts a lesser force but theabove referred-to torque arm increases. These two factors tend toneutralize each other to the effect that the outward pressure at theends of the arms 26 remains nearly constant. As may be seen in FIG. 2the collar 14 has a sufficient outer diameter that it extends outwardlybeyond the tips 26 of the arms in all operating postons of the arms.

Extending outwardly, or to the right as viewed in FIGS. 4 and 5, fromthe base 23 of each arm is a strip portion 23a. As is readily seen inFIG. 4, the strip portion 23:: has a double bend adjacent its juncturewith the channel shaped portion such that the strip portions 23a of thetwo arms are offset toward each other and may come substantially intocontact with each other when the arms pivot inwardly, as illustrated inFIG. 3. Such offsetting permits sufficient pivoting of the carriers,

.for self-alignment when the arms are in their inner positionsthroughout the range of movement of the arms. The free end of each stripportion 23a is bent outwardly as seen in FIG. 4 for a purposehereinafter explained, and includes a pair of ears 30 extendinglaterally therefrom on which a honing unit is carried as hereinafterdescribed.

' Each honing unit 31 includes a hone carrier 38 of generally channelshaped form, having a channel base or web 32 and channel legs or flanges33. Each flange 33 has an open ended keyhole slot 34, oriented as shownin FIG. 7, the two slots of each carrier being laterally aligned. Theflanges 33 of each hone carrier 33 are spaced apart a sufficientdistance that the strip portion of the free end of the corresponding armmay be freely received therebetween. The ears 30 of the arms, however,are positioned to extend through enlarged portions of the slots 34- andpreferably sufiiciently beyond the flanges 33 whereby the carriers maypivot on the ears 30 and are retained on the arms.

A suitable stone 36 or other suitable abrasive element is secured to theouter surface of the web 32 of each carrier 38 as by a suitableadhesive.

In assembling the honing units 31 on the arms 20, the ears 36 are slidthrough the narrow portions of the keyhole slots 34 and into theenlarged or circular portion thereof. A tip 35 defining one side of thenarrow portion of the keyhole slot 34- is then deformed such that theslot is substantially closed as illustrated in FIG. 8. The material ofthe hone carrier and the dimensions thereof are preferably such that thetip 35 may be thus distorted by use of ordinary pliers or merely bypressure of a screw driver thereagainst. In the preferred embodiment thehone carrier is formed of sheet metal and is proportioned as shown inFIG. 7, which is twice actual size. With this construction, the tips 35are readily bent down to close the slots. The circular portions of thekeyhole slots 34 must be of such size as to receive freely thecorresponding ears 30, after the keyhole slots have been closed, inorder that the carrier may pivot freely on the arm.

Pivotal movement of the units 31 on the arms 20 in one direction(counterclockwise as viewed in FIG. 1) is limited by engagement of thechannel portions 32 thereof with the arms 20. Accordingly, it isdesirable that the length of the planar portion of the arm extendingoutwardly of the offset therein be of sufficient length that the innerends of the hone carriers are engageable only with the inwardly offsetportions of the arm, as shown in FIG. 3. With this arrangement the arms20 do not interfere with the pivotal movement of the hone carriers, andthe latter may assume parallel positions when the device is reduced toits smallest possible diameter.

Pivotal movement of the hone carriers in the opposite direction withrespect to the arms 20 (clockwise, as viewed in FIG. 1) is limited byengagement of the tip of each arm with a tab 37 which is punchedinwardly from the base 32 of the corresponding carrier 38, as best seenin FIG. 8. The tip of each arm is preferably bent outwardly as shown inFIG. 4 for this purpose and serves to bolt the units in poistionsgenerally parallel to the axis of the drive stem 12. These parts are sodimensioned as to avoid interference with proper alignment of the honingunits at the most widespread position, illustrated in FIG. 1. Thepurpose of limiting pivotal movement in this other direction is topermit ease of insertion of the honing units in a cylinder and toprevent them from assuming such positions that the operator might insertthe honing device into a cylinder with the abrasive elements facinginwardly.

The honing units 31 must be assembled in proper endto-end relationshipwith the corresponding arms 20 in order that the tabs 37 be properlypositioned for engagement with the tips of the arms. Analysis of FIGS. 3and 8 reveals, however, that the ears 30 of an arm 20 cannot be insertedinto the keyhole slots of a hone carrier if the latter is improperlyturned end-for-end. Accordingly, improper assembly is prevented.

Because of the fact that the inner or channel-shaped ends of the armsZtl are necessarily staggered by virtue of the overlapping of thechannel legs thereof, there tends to the off-center positioning of thehoning units 31 with respect to the drive stem 12. This is preferablycompensated for by the configuration of the arms 20. As may be seen bestin FIGS. 2 and 5, the outer or strip portions of the arms 20 are formedsuch that the axes thereof are offset in a direction opposite the abovereferred-to offset of the channel-shaped ends. Accordingly, the honingunits 31 are centrally positioned with respect to the drive stem 12.

In operation, the shank 11 is inserted in the chuck of an electricdrill, for example a conventional handheld drill, and the chuck istightened. The knurled nut 15 is adjusted to produce the desiredpressure of the homes against the cylinder walls. As is well understoodin the art, a higher pressure tends to produce a grinding effect whereasa lighter pressure produces more of a polishing effect. The operator maybring the arms 24 and the honing units 31 toward each other suflicientlyto permit their insertion into the cylinder to be honed simply by manualsqueezing together of the inner or channel-shaped portions of the arms20. When the hone carriers have been inserted into the cylinder to behoned he may release the arms, and the spring 17 and collar 14 willbring the honing elements 36 into engagement with the cylinder walls. Asindicated above, there is no possibility that the honing units 31 willpivot about the ears 30 to such an extent that the honing elements 36will face inwardly rather than outwardly, since pivotal movement of thehoning units 31 is limited with respect to the arms 2.1) in bothdirections. The electric drill may then be started and the honingelements 36 will be driven around the cylinder walls while bearingagainst the walls with selected pressure. The drill may be moved axiallywith respect to the cylinder such that any desired length of thecylinder may be honed. The abrasive elements 36 may reach the extremedepth of the cylinder (limited only by the length of the drive stem 12,flexible shaft 13, and shank 11), and may hone the extreme outer portionof the cylinder since the ends of the honing elements 36 extendingtoward the drive stem 12 may be permitted to extend slightly beyond thelip of the cylinder without undesired effect.

A second form of honing unit is illustrated in FIG. 9 to which referencenow is made. The unit 50 includes a carrier 51 of generallychannel-shaped form having a web 52 with flanges 5'3 and 54 extendingperpendicularly therefrom in spaced relation. The flanges 53 and 54 areprovided with aligned circular openings 55 at the longitudinal midpointsthereof for receiving the ears 30 of the carrying arm 20 (such as shownin FIGS. 1 to 6).

One of the flanges, for example, the flange 54, is provided with spacednotches 56, 56 on either side of the opening 55 which extend preferablysubstantially throughout the depth of the flange and which define atongue 57. The tongue thus can be bent readily out of the plane of theremainder of the flange 54 without bending the remaining portions of theflange, which, as seen in FIG. 9 are located on opposite sides of thetongue 57. The carrier 51 is provided with a tab 59 formed and arrangedin a manner similarly to the tab 37 above described and for the samepurpose.

An abrasive element such as a stone 58 is suitably secured, as by anadhesive to the outer face of the web 52, as seen in FIG. 9.

The carrier 51 preferably is formed with the tongue 57 in the plane ofthe remainder of the flange 54 and the tongue 57 is then bent outwardlyfrom such plane, as indicated in broken lines in FIG. 10.

The honing unit 59 is attached to the corresponding arm 20 by insertingthe appropriate ear 30 of the arm 20 in the opening 55 formed in theunnotched flange 53. The arm is then positioned to place the other ear30 in alignment with the opening 55 in the tongue 57 which is at thattime bent out as indicated in broken lines in FIG. 10. The tongue 57 isthen bent inwardly, as by the use of an appropriate tool, such as a pairof pliers, into the plane of the remainder of the flange 54, whichaction causes the opening 55 in the tongue 57 to receive the car 30.This results in the flanges 53 and the tongue 57 being brought intoparallelism so that the ears 30 are received in the openings 55 and theunit 50 thus securedly attached to the end of the arm 25 Preferably theunit is so oriented with respect'to the arm 2'9 that the unnotchedflange 53 is in the leading or pressure side of the arm. Thus, thepressure which might tend to bend the flange outwardly and thus possiblydislodge the unit from the arm is applied to the stiff flange 53 and thepossibility of dislodgement is minimized.

A honing device has now been disclosed which serves the purposes ofdevices of this general character while employing only two honing units.The use of only two honing units combined with the channel-shaped innerends of the arms makes it possible for the device to be used for honinga very small cylinder. More particularly, the device may hone a cylinderwhich will encompass the two relativel flat hone carriers. As oppose tothis, any honing device employing three honing units, as is common inthe art, cannot be employed to hone as small a cylinder since the threehoning units must, at minimum size, form a triangle. The minimum size ofcylinder which can encompass three honing elements arranged in atriangle is necessarily substantially larger than the minimum size ofcylinder which can encompass two of the same honing units arranged backto back. Furthermore, all other portions of the device are of suchdimensions that the device may be stored in a very small space when theknurled nut is turned in such a direction as to release the spring 17.

In the honing device described above, the arms and hence the honingunits are driven positively by the shaft through pin 21. This is opposedto various previously known honing devices in which the arms arearranged in slots which, of necessity, receive the arms quite loosely.Further-more, there is little friction involved in the pivotal movementof the arms and of the hone carriers in the device described abovewhereas in many prior art devices substantial friction accompanies thesepivotal movements.

A novel form of connection between the honing units and thecorresponding arms has also been disclosed. This connection permits freepivotal movement of the hone carriers with respect to the associatedarms while involving very simple construction and permitting convenientassembly and disassembly without the use of special tools.

Finally, it will be apparent that a honing device constructed inaccordance with the present invention is in its entirety of very simpleconstruction and therefore inexpensive to manufacture while havingvarious other advantages over prior art devices.

It will be apparent that the invention may be varied in its physicalembodiment without departing from the spirit of the invention, and it isdesired, therefore, that the invention be limited only by the scope ofthe appended claims.

The invention having thus been described, what is clairned and desiredto be secured by Letters Patent is:

1. A honing device comprising a drive stem, a collar slidably supportedon said stem, and having an end face perpendicular to said stem a nutthreadedly engaging said stem, a spring compressed between said nut andsaid collar, a pair of hone carriers, a pair of arms each pivotallysupporting adjacent one end thereof one of said carriers and beingpivotally connected adjacent the other end thereof to said stem, saidarms each having a channel portion adjacent said other end and beingarranged with said channel portions opening toward each other and withthe flanges of said channel portions overlapping, said flanges havingbeveled ends extending beyond the web of said channel portions, a pinextending through overlapping portions of said flanges and through saidstem adjacent one end thereof, whereby said arms may pivot fromsubstantially parallel positions outward to spread positions, saidcollar bearing at said end face against the beveled ends of said flangesthrough action of said spring and thereby urging said arms toward spreadposition.

2. A honing device comprising a drive stem, a collar siidably supportedon said stem, and having an end face perpendicular to said stem a nutthreadedly engaging said stem, a spring compressed between said nut andsaid collar, a pair of hone carriers, 21 pair of arms each having asubstantially planar outer end pivotally supporting one of said carriersand ,a channel shaped inner end portion pivotally connected to saidstem, said arms being arranged with said channel portions opening towardeach other and with the flanges of said channel portions overlapping,said flanges having beveled inner ends and extending inwardly beyond thewebs of said channel portions, a pin extending through overlappingportions of said channel flanges and through said stem adjacent one endthereof, whereby said arms may pivot from substantially parallelpositions outward to spread positions, said collar bearing at said endface against the beveled inner ends of said channel flanges throughaction of said spring and thereby urging said arms toward spreadposition, said outer substantially planar portions of said arms beingoffset toward each other whereby they may move substantially intocontact with each other.

3. A honing device comprising a drive stem, a collar slidably supportedon said stem, and having an end face perpendicular to said stem a nutthreadedly engaging said stem, a spring compressed between said nut andsaid collar, a pair of hone carriers, a pair of arms each having asubstantially planar outer end portion pivotally supporting one of saidcarriers and a channel shaped inner end portion pivotally connected tosaid stem, said arms being arranged with said channel portions openingtoward each other and with the flanges of said channel portionsoverlapping, said flanges having beveled inner ends and extendinginwardly beyond the webs of said channel portions, a pin extendingthrough overlapping portions of said channel flanges and through saidstem adjacent one end thereof, whereby said arms may pivot fromsubstantially parallel positions outward to spread positions, saidcollar bearing at said end face against the beveled inner ends of saidchannel flanges through action of said spring and thereby urging saidarms toward spread position, said outer substantially planar portions ofsaid arms being offset toward each other near their extremities wherebythey may move substantially into contact with each other, said honecarriers being channel shaped and having channel sides spacedsufliciently to receive said outer arm portions freely therebetween,each of said outer arm portions having a pair of laterally projectingears, each of said hone carriers having opposed, open-ended keyholeslots in opposite sides thereof for receiving said ears, said wallsbeing readily deformable to close said slots.

4. A honing device comprising a drive stern, a collar slidably supportedon said stem, and having an end face perpendicular to said stem a nutthreadedly engaging said stem, a spring compressed between said nut andsaid collar, a pair of hone carriers, a pair of arms each having asubstantially planar outer end portion pivotally supporting one of saidcarriers and a channel shaped inner end portion pivotally connected tosaid stem, said arms being arranged with said channel portions openingtoward each other and with the flanges of said channel portionsoverlapping, said channel portions having beveled inner ends andextending inwardly beyond the webs of said channel portions, a pinextending through overlapping portions of said channel flanges andthrough said stem adjacent one end thereof, whereby said arms may pivotfrom substantially parallel positions outward to spread positions, saidcollar bearing at said end face against the beveled inner ends of saidchannel flanges through action of said spring and thereby urging saidarms toward spread position, said outer substantially planar portions ofsaid arms being offset toward each other near their extremities wherebythey may move substantially into contact with each other, said honecarriers being channel shaped and having channel sides spacedsufficiently to receive said outer arm portions freely therebetween,means pivotally supporting said hone carriers on said outer arm portionsof said arms respectively pivotal movement of said hone carriers withrespect to said arms being limited in one direction by engagement of thebases of said carriers with the corresponding arms, the base portion ofeach of said channel shaped hone carriers including a tab engageablewith the portion of the corresponding arm outwardly beyond said piovtalmeans to limit pivotal movement in the other direction when said arm issubstantially normal to the honing surface of the homes carried by saidhoning carriers.

5. A honing device comprising a drive stem, a collar slidably supportedon said stem, and having having an end face perpendicular to said stem anut threadedly engaging said stem, a spring compressed between said nutand said collar, a pair of hone carriers, a pair of arms each pivotallysupporting adjacent one end thereof one of said can riers and beingpivotally connected adjacent the other end thereof to said stem, saidarms each having a channel portion adjacent said other end and beingarranged with said channel portions opening toward each other and withthe flanges of said channel portions overlapping, said channel portionshaving beveled ends and extending inwardly beyond the webs of saidchannel portions, a pin extending through overlapping portions of saidchannel legs and through said stem adjacent one end thereof, wherebysaid arms may pivot from substantially parallel positions outward topread positions, said collar bearing at said end face against thebeveled inner ends of said channel flanges through action of said springand thereby urging said arms toward spread position, said hone carrierseach being channel shaped and having channel sides spaced suflicientlyto receive said one end of one arm freely therebetween, each of saidarms having adjacent said one end a pair of laterally projecting ears,each of said hone carriers having opposed, open-ended keyhole slots inopposite sides thereof for receiving said ears, said walls beingpermanently deformable to close said slots.

6. A honing device comprising a drive stem, a collar slidably supportedon said stem, and having an end face perpendicular to said stem a nutthreadedly engaging said stern, a spring compressed between said nut andsaid collar, a pair of hone carriers, a pair of arms each pivotallysupporting adjacent one end thereof one of said carriers and beingpivotally connected adjacent the other end thereof to said stem, saidarms each having a channel portion adjacent said other end and beingarranged with said channel portions opening toward each other and withthe flanges of said channel portions overlapping, said channel portionshaving beveled ends and extending inwardly beyond the webs of saidchannel portions, a pin extending through overlapping portions of saidchannel legs and through said stem adjacent one end thereof, wherebysaid arms may pivot from substantially parallel positions outward tospread positions, said collar bearing at said end face against thebeveled inner ends of said channel flanges through action of said springand thereby urging said arms toward spread position, said hone carrierseach being channel shaped and having channel sides spaced suflicientlyto receive said one end of one arm freely therebetween, each of saidarms having adjacent said one end a pair of laterally projecting ears,each of said hone carriers having opposed, open-ended keyhole slots inopposite sides thereof for receiving said ears, said walls beingpermanently deformable to close said slots, pivotal movement of saidhone carriers with respect to said arms being limited in one directionby engagement of the base of said carriers with the corresponding arms,the base portion of each of said channel shaped hone carriers includinga tab engageable with the outer portion of the corresponding armoutwardly beyond said pivotal means to limit pivotal movement in theother direction.

7. A honing device comprising a drive stem, a collar slidably supportedin said stem, and having an end face perpendicular to said stem a nutthreadedly engaging said stem, a spring compressed between said nut andsaid collar, a pair of hone carriers, a pair of arms each pivotallysupporting adjacent one end thereof one of said carriers and beingpivotally connected adjacent the other end thereof to said stem, each ofsaid arms having two generally parallel, spaced apart walls adjacentsaid other end and overlapping the walls of the other arm, a pinextending through overlapping portions of said walls and through saidstem adjacent one end thereof, whereby said arms may pivot fromsubstantially parallel positions outward to spread positions, said wallshaving bevelled ends against which said end face of said collar may bearthrough action of said spring and thereby urge said arms toward spreadposition.

8. A honing device comprising a drive stem, pivot means projectingdiametrically from said stem adjacent an end thereof, a pair of arms,each including a channel portion having a flat strip extending from oneend of the web and flange extensions extending beyond the web at theother end, said flange extensions being mutually overlapping instraddling relation to said stem and receiving said pivot meanstherethroug-h, a longitudinally adjustable abutment on said stem, acollar slidably carried on said stem between said abutment and saidpivot means and having a planar end wall perpendicular to the axis ofsaid stem and positioned to bear against the end edges of said flangeextensions, a spring compressed between said abutment and said collar,each pair of flange extensions having their inner end edges inclined inopposite directions to cause the outer ends of said arms to be urgedoutwardly apart by said spring, and an abrasive honing unit pivotallycarried at the outer ends of each of said web extensions.

9. A honing device comprising a drive stem, pivot means projectingdiametrically from said stem adjacent an end thereof, a pair of arms,each including a channel portion having a web extension at one end andflange extensions at the other end, said flange extensions beingmutually overlapping and receiving said pivot means therethrough, alongitudinally adjustable abutment on said stem, a collar slidablycarried on said stem between said abutment and said pivot means andhaving a planar end wall perpendiculr to the axis of said stem andpositioned to bear against the end edges of said flange extensions, aspring compressed between said abutment and said collar, the extensionsof each pair of flanges having their end edges inclined oppositely andin a direction to make an acute angle with the free side edge of theflange thereby to cause the outer ends of said arms to be urgedoutwardly apart by said spring, and an abrasive honing unit pivotallycarried at the outer ends of each of said web extensions.

10. A honing device comprising a drive stem, a pair of arms each havinga channel portion with the flanges extending beyond the web in onedirection and having inclined end edges and a resilient elongate stripportion extending from the web of said channel portion in the oppositedirection, hone carriers pivotally carried on the outer ends of saidarms, means projecting diametrically from said stem and through theextending portions of said flanges for pivotally supporting said arms onsaid stem with said channel portions in opposed relation and eachstraddling said stem and extending on both sides of the axis of saidstem, a collar slidable on said stem and having an end faceperpendicular to the axis of said drive stem and positioned to engagethe end edges of said flanges which extend beyond said web, an abutmentadjustable longitudinally on said stem and a spring compressed betweensaid abutment and said collar for yieldably urging said collar in adirection to swing said arms outwardly.

11. A honing device comprising a drive stem, a pair of arms each havinga channel portion with the flanges extending beyond the web in onedirection and having end edges inclined at an acute angle to the treeside edge of the flanges, and a resilient elongate strip portionextending from the web of said channel portion in the oppositedirection, hone carriers pivotally carried on the outer ends of saidarm, means projecting diametrically from said stem and through theextending portions of said flanges for pivotally supporting said arms onsaid stem with said channel portions in opposed relation and eachstraddling said stem and exciting on both sides of the axis of saidstem, a collar slidable on said stern and having an end faceperpendicular to the axis of said drive stem and positioned to engagethe end edges of said flanges which extend beyond said web, an abutmentadjustable longitudinally on said stern and a spring compressed betweensaid abutment and said collar for yieldably urging said collar in adirection to swing said arms outwardly.

References Cited in the file of this patent UNITED STATES PATENTS723,818 Brewington Mar. 31, 1903 1,474,649 Storm Nov. 20, 1923 2,056,777Evans Oct. 6, 1936 2,128,822 Horne Aug. 30, 1938 2,196,542 Zaiger Apr.9, 1940 2,404,523 Nesson July 23, 1946 2,736,146 Brooks Feb. 28, 19562,778,168 Clark Jan. 22, 1957 2,782,572 Clark Feb. 26, 1957 2,805,528Barrett Sept. 10, 1957

